Blasting cartridge



J. BARAB BLASTING CARTRIDGE Aug. 29,` 1944.

Filed April 18, 1941 l l l l I l l l l Flc.-

JACOB BARAB INV ENTOR.

-mites of various types.

Patented Aug. 29, 1944 FFEQE 'raar Las'rrNG CARTRIDGE Jacob Bai-ab, Wilmington, Del., assigner to Hercules Powder Company, Wilmington, Del., a

corporation of Delaware Application April 18, 1941, Serial No. 389,125

10 Claims.

This invention relates to an improved blasting cartridge and to methods of production thereof; It relates more particularly to a blasting cartridge embodying a cushioning sheath which is especially advantageous in the mining of coal.

It is thel principal object of this invention to provide a blasting cartridge enclosed in a sheath comprising a compressible cushioning material and a flame-quenching or cooling salt. The cushioning material acts to absorb the initial shattering shock produced by firing the explosive. The cooling salt exerts a cooling or quenching eiect on the gases and flame produced, thereby reducing hazards in the mine.

The sheathing of a blasting cartridge with a compressible cushioning material in accordance with this invention is of particular importance' .for explosive cartridges to be used in coal mining. After the initial shock from `the explosive has been absorbed by the cushioning material, the expanding gases released by the explosion search out the cleavage planes of the coal. The result is a pushing action which breaks up the structure in such a mannerthat large, iirm lumps are formed. Without the cushioning material, a much larger amount of pulverized coal is produced.

The improvement in blasting cartridge described in accordance with thisl invention may be accomplished with any desired form of explosive, but will be found most advantageous in connection with, for example, permissible dyna- The shattering eiect of such explosives when red in direct contact with coal is very undesirable. Use of permissible explosives in the process further reduces the liability of ignition' of combustible gas mixtures and coal dust.

Theimproved explosive cartridge which provides the advantages related above in the mining of coal may be produced in accordance with the present invention by surrounding the cartridge with a sheath comprising a. non-combustible compressible material, such as, for example, expanded mica. pellets or a combustible' compressible material such as, for example, balsa, bagasse, cork, etc., and a llame quenching salt suchas, for example, sodium bicarbonate, plaster of Paris, borax, calcium uoride, etc. The sheath comprising the above ingredients may desirably be preformed to t around the cartridge. The sheath may take the form of castings of semi-circular sections which may be iitted around the cartridge.

It may be a tube prepared by` extrusion of a composition comprising the above ingredients. It may take the form of a blanket of the compressible cushioning material containing a layer of cooling salt between two layers of the cushioning material. The sheath may likewise consist of a tube of corrugated shape comprising the above ingredients, the advantage of corrugations being the added air cushioning effect provided by the air pocketed therein. Also, the sheath mayl consist of an annular space provided around the explosive Icartridge by means of, for example, an outside paper. The compressible cushioning substance and the cooling salt may then be loaded in the form of pellets, powder or .granules into the annular space between the cartridge and the surrounding outside paper.

Having now indicated in a general way the nature and purpose of this invention, there follows a more detailed description of preferred .embodiments thereof with reference to the accompanying drawing in which Fig. 1 represents a cushioning sheath partially in section and containing an explosive cartridge, and Fig. 2is a. View of the cushioning sheath of Fig. 1, on line 2-2.

Referring now to the drawing, the assembled article of this invention comprises a blasting cartridge I surrounded by' a. cushioning sheath 2 comprising a packed, homogeneous material 3 retained in position by asurrounding tube t. The y explosive cartridge I comprises an explosive composition 5 wrapped in paper 6 which is crimped I at the end.

If desirable, a cap 8 maybe placed over either inserted in the end of the sheath 2 proper. In

such instances the sheath 2 will be slightly longer than the explosive cartridge which is to be used. The plug may be retained -by any adhesive. taping or similar expedient.

The thickness of the cushioning sheath may be varied to provide varied amounts of cushioning eiiect. AA thickness of about 1/8 inch to about 3A inch is desirable for most purposes. Thus, a sheath to t around a 11A" x 8" dynamite cartridge will be about 1352 inches inside diameter and about 139, inches to about 12%2 inchesoutside diameter.

The sheath may be of about the same length as the cartridge and'may be open at both ends to provide propagation of the explosion to, another cartridge. The ends of the cartridge may, however, be closed with plugs or discs of the sheathing composition. With the latter arrangement propagation of the explosion to another cartridge is greatly reduced. This arrangement is preferable where only one cartridge is used in a borehole.

The compressible cushioning material and the flame-quenching or cooling salt may be fabricated into the sheath by moistening .the dry composition, then molding and drying the sheath A binding agent may be incorporated to bind the ingredients together. The binding agent may also be a cooling salt, such as plaster of Paris.

Other binding agents, such as, for example, sodium silicate, dextrin, clay, etc. may be used.

In the cushioning sheath it will be desirable v to include about to about 30% of compressible material and about 40% to about 90% oi' flame-quenching salt. 'I'he binding material added will be coordinated to give the desired cohesion and tofaciiitate packing.

To illustrate the sheathing of an explosive cartridge to provide the cushioning 'and flame quenching or cooling effects described, the following examples are cited: Y

' Example I A mixture consisting of 65% by weight of eodium bicarbonate, by weight of Balsa pulp and 15% by weight of clay was moistened with an equal weight of a 10% by weight aqueous solution of sodium bicarbonate. This composition -assignee space of V4 inch thickness. The extruded'tube Y had a length of about a inches. It was dried in an oven at a temperature of about 150 F. forv about 20 hours with the dowel inside. The dowel was then removed and a 1%" x 8" dynamite cartridge was inserted in the extruded tube, thecnds sealed with gum kraft paper and the sheathed.

cartridge dipped in Paraiiln.

' Example V A mixture consisting of 20 percent by weight of bagasse and 80 percent by weight of plaster of Paris was pelleted by moistening the dry composition and agitating the mixture while it was setting. After drying for about 5 hours at a temperature of about130 F. the dry pelleted mateiiitlV was poured into the annular space between a 1]/4" x 8" dynamite cartridge and an outer paper shell 13/4 inches in diameter. The. paper on the ends was folded over and the sheathed cartridge dipped in parafn.

The sheaths prepared as described in the above examples after drying are semi-rigid and have suillcient strength to withstand any normal handling necessary in manufacture and use. The sheaths have a cellular, favose structure which gives the cushioning action desirable and produces lump material in blasting operation such as coal mining.

-In the above examples, each end of the sheathed cartridge may be fitted with a plug or disc' of the cushioning composition used. The plug or was molded into semi-circular half-sheaths about d inches in length and of such size that two of the half-sheaths join to give a sheath of about 1% inches insidediameter and about 1% inches outside diameter. The mold was lined with paper.l About 95 gramsofwet composition were' required for a half-sheath. The molded haltsheaths were dried for about 20 hours on dowels at a temperature of about 130 F. The dowels and inner paper were then removed from the half-sheaths and the latter dried further in air.

Two of the half-sheaths prepared as described above were then sealed aroimd a 1%" x 8" dynamite cartridge with the aid of mucilage. Strips of gum kraft paper were sealed over each end of disc may have a thickness equal to the thickness of the cushioning sheath, for example, about inch to about V4 inch. It may have a diameter equal to that of the dynamite cartridge itself, in which case it may tlt into the end of the sheath.

' It may, if desirable, have a diameter equal to the sheathed dynamite cartridge. The latter was then dipped in parafiln,

Example II A mixture of parts of sodium bicarbonate, ioparts by weight Balsa and 30 cc. of a dextrin solution was packed into an annular sheath and tions in the compositions and procedures ernvplo'yed may be made without departing from the dried for about one day at a temperature of about unit dipped in paraiiin. v

:compie m A mixture comprising 80 partsby weight sodium chloride, 20 parts by weight bagasse was moistened with 50 cc. of aqueous sodium silicate.

F., a dynamite cartridge inserted and the This composition was formed into a sheath, dried and an explosive cartridge inserted thereinto.

sample 1vv A mixtureconsisting of 'I5 percent by weight of sodium bicarbonate, 25jpereent by weight of cork,

.1045 mesh, and 35 cc.' of ay binder solution ycon-v taining dextrin was mixed and then extruded through a nozzle inside a prefabricated paper shell having a dowel inside to provide an annular,

the outside diameter of the cushioningsheath, in which case it will ilt over the end of the sheath. The plug or disc may be secured at each endy by any convenient means such as, for example, byl

sealing .with gum kraft paper.

When used in coal mining the sheathed, cushioned cartridge produced as described in the above examples will provide an improved quality and quantity of lump coal over that obtained with an unsheathed and uncushioned cartridge.

It will be appreciated that the above details and examples are given merely for tlm purposes of illustratingmy invention and are not intended to limit the invention. Moreover, many variascope of the invention.

This application is a continuation-impart of my application, Serial No. 25,342.` filed August 17, 1938, now U. B. Patent N0. 2,277,059.

what 1 oieim end desire to protect by Letters Patent is: e

l. A n improved blasting assembly including `an explosive cartridge surrounded by a preannular, tubular. sheath comprising' and cork, a binder, and from about 40% to about 90% of a flame-quenching saltsaid sheath characterized by a semi-rigid, cellular, favose structure which is adapted to provide`a cushioning action for the initialexplosive shock.

3. An improved blasting assembly including an explosive cartridge surrounded by a preformed, annular, tubular sheath comprising from about 10% to about 30% of a carbonaceous material selected from the group consisting of balsa, bagasse and cork,-dextrin, and from about 40% to about 90% of a. `name-quenching salt, said sheath characterized by a semi-rigid, cellular, favose structure which is adapted to provide a cushioning action for the initial explosive shock.

4. An improved blasting assembly including anv explosive cartridge surrounded by a preformed.

annular, tubular sheath comprising from about 10% toabout 30% of a carbonaceous material selected from the group consisting of balsa, bagasse and cork, and from about 40% to about I 90% of sodium bicarbonate, said sheath characterized by a semi-rigid, cellular, favose structure which is adapted to provide a cushioning action for the initial explosive shock.

5. An improved blasting assembly including an explosive cartridge surrounded by a preformed, annular, tubular sheath comprising from about 10% to about 30% of balsa and from about 40% to about 90% ofv a flame-quenching salt, said sheath characterized by a semi-rigid, cellular, favose structure which is adapted to provide a cushioning action for the initial explosive 6. An improved blasting assembly including an explosive cartridge surrounded by a preformed, annular, tubular sheath comprising from about 10% to about 30% of bagasse and from about 40% to about 90% of a name-quenching salt, said sheath characterized by a semi-rigid, cellular, favose structure which is adapted to provide a cushioning action for the initial explosive shock. l y

7. An-'amproved blasting assembly including an explosive cartridge surrounded by a preformed, annular, tubular sheath comprising from about 10% to about 30% of cork and from about 40% to about 90% of a name-quenching salt, said sheath characterized by a' semi-rigid, cellular, favose structure which is adapted to provide a cushioning action for the initial explosive shock.

8. An improved blasting assembly including an explosive cartridge surrounded by a preformed, annular, tubular sheath comprising from about 10% to about 30% of balsa and from about.

40%v to about 90% of sodiumbicarbonate, said sheath characterized by a semi-rigid, cellular,

favose structure which is adapted to provide a cushioning action for the initial explosive shock.

9. An improved`blasting assembly including an explosive cartridge surrounded by a pre- .formed, annular, tubular sheath comprising from about 10% to about 30% of bagasse land from about 40% to about 90% of sodium bicarbonate, said sheath characterizedby a semi-rigid, cellular, favose structure which is adapted to provide a vcushioning action for the initial explosive shock.,

10. An improved blasting assembly including an explosive cartridge surrounded'by a preformed, annular, tubular sheath comprising from about 10% to about 30% of cork and from about 40% toabout 90% of sodium bicarbonate, said Sheath vcharacterized by avsemi-rigid, cellular, favose structure which is adapted to provide a cushioning action for the initial explosive shock. g JACOB BARAB. 

